1. Field of the Invention
The present invention relates to a plasma processing apparatus and a plasma processing method for processing a substrate by generating plasma in a process vessel.
2. Description of the Related Art
In manufacturing processes of, for example, a semiconductor device, a liquid crystal display device, and the like, plasma processing by a plasma processing apparatus is widely used as processing such as etching and film deposition to a semiconductor wafer. Such a plasma processing apparatus includes, in a process vessel, upper and lower electrodes facing each other, and radio frequency power is supplied to the lower electrode on which, for example, a substrate is placed to generate plasma between the lower electrode and the upper electrode, thereby processing the substrate.
In this plasma processing apparatus, to increase product yields, it is necessary to enhance wafer in-plane uniformity of the processing by controlling density distribution of the plasma generated in the process vessel. As one measure for this, the present applicant has disclosed a method to change impedance to a fundamental wave supplied from a radio frequency power source and its harmonics, on the electrode side of the plasma generated in the process vessel (see, Japanese Patent Application Laid-open No. 2004-96066).
In the process vessel of the plasma processing apparatus, the fundamental wave of the radio frequency power supplied to the electrode and various high-order harmonics of the fundamental wave are generated during the plasma processing. According to the method disclosed in the above Japanese Patent Application Laid-open No. 2004-96066, the impedance to the fundamental wave from the radio frequency power source and its harmonics, on the electrode side of the plasma generated in the process vessel is varied so as to selectively resonate the fundamental wave and its harmonics, so that it is possible to maintain high in-plane uniformity of the plasma processing to the semiconductor wafer and stably maintain the state of the plasma in the process vessel.